Read the docs
TI-2026-26830 Aliases CVE-2026-34582

Botan has a TLS 1.3 certificate authentication bypass

Priority MEDIUM 43CWE-841Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
None
Attack complexity
Low
Attack requirements
None
Impact type
—
Confidentiality · integrity · availability
None · High · None
Fix status
Fixed

Attack profile from CVSS 4.0 · CNA. Fix status from CNA.

Summary

Botan is a C++ cryptography library. Prior to version 3.11.1, the TLS 1.3 implementation allowed ApplicationData records to be processed prior to the Finished message being received. A server which is attempting to enforce client authentication via certificates can by bypassed by a client which entirely omits Certificate, CertificateVerify, and the Finished message and instead sends application data records. This vulnerability is fixed in 3.11.1.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00242 15th percentileScored 2026-11-07
Fix Fixed botan (randombit): 3.11.1

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
Yes
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
randombitbotanbefore 3.11.13.11.1Patch availableCNA
  • botan Vendorrandombit Affected before 3.11.1 Fixed in 3.11.1 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:botan_project:botan:*:*:*:*:*:*:*:*3.0.0 – 3.11.0Vulnerablerandombit
  • cpe:2.3:a:botan_project:botan:*:*:*:*:*:*:*:* Versions 3.0.0 – 3.11.0 Vulnerable ·randombit

Remediation

  • Fix · CNA botan (randombit) Fixed in 3.11.1

Vendor assessments

Red Hat

Red Hat rating: Important. Red Hat's page for this CVE →

Not affected: 1 product
  • Red Hat Enterprise Linux 10

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-34582

References

Advisory 1

  • TI-2024-33818 Botan before 3.6.0, when certain GCC versions are used, has a compiler-induced… CVSS 3.1MEDIUM 5.9
  • TI-2024-33817 Botan before 3.6.0, when certain LLVM versions are used, has compiler-induced… CVSS 3.1MEDIUM 5.9
  • TI-2016-02004 Integer overflow in the PointGFp constructor in Botan before 1.10.11 and 1.11.x before… CVSS 3.0CRITICAL 9.8
  • TI-2016-02005 Heap-based buffer overflow in the P-521 reduction function in Botan 1.11.x before 1.11.27… CVSS 3.0CRITICAL 9.8
  • TI-2026-26828 Botan has a certificate authentication bypass due to trust anchor confusion CVSS 4.0CRITICAL 9.3
  • TI-2016-07479 In Botan 1.8.0 through 1.11.33, when decoding BER data an integer overflow could occur… CVSS 3.0CRITICAL 9.8
See all 34 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences